I think part of the reason these people might feel this way is because when you look at the fundamentals, Israel was a really really stupid idea. The premise that one group has a right to some land because their ancestors lived there 2000 years ago is quite laughable. That's why I've always considered Zionism as absurd as the drivel written by Ayn Rand and about equal in what value it brings to public discourse.
And it doesn't help that Israel was founded by some pretty disgusting people, can anyone explain what makes the Irgun and Lehi in any way better than Hamas?
At least the Israeli's made something out of the country, as opposed to turning it into another middle-eastern s**tbox a la Syria, Libya, Iraq, Iran.